Process for hydrofining bitumen derived from tar sands



J. ENG ETAL Nov. l25, 1969 PROCESS FOR HYDROFINING BITUMN DERIVED FROM TAR SANDS Filed March 16, 1967 IE5 l 233 United States Patent C) 3,480,540 PROCESS FOR HYDROFINING BITUMEN DERIVED FROM TAR SANDS Jackson Eng and William R. Guggisberg, Sarnia, Ontario, Canada, assignors to Esso Research and Engineering Company, a corporation of Delaware Filed Mar. 16, 1967, Ser. No. 623,621 Int. Cl. C10c 1/20; C10g 31/14, 23/00 U.S. Cl. 208-93 11 Claims ABSTRACT OF THE DISCLOSURE Process for hydroning bitumen derived from tar sands comprising blending virgin fractions and cracked fractions, hydroning the blend and recovering hydroned products.

This invention relates to a process for hydrofining bitumen derived from tar sands.

Bituminous sand or tar sand deposits are presently being mined for recovery of valuable hydrocarbon constituents. Following removal of sand, clay and water a tar or bitumen is processed to produce a semirened crude oil or synthetic crude oil which can be transported by pipeline. Preferably the bitumen is at least partially processed at the mining site to provide an oil suitable for transportation in a pipeline.

It has been proposed that the entire bitumen be cracked and then distilled to provide a naphtha fraction, a light gas oil fraction and a heavy gas oil fraction. These fractions are separately hydroned in three units and the treated fractions are blended to provide a treated synthetic crude oil which is transported to a conventional petroleum refinery. Separate hydroners are used because it is felt that hydroiining conditions and catalysts tailored to the various distillate fractions are required to obtain fractions suitable for further processing.

The object of the present invention is to provide a hy- 4drolning process which will provide adequate desulfurizaling the bottoms fraction, blending the virgin and cracked fractions, hydroning the blend and recovering desired product fractions.

The invention will be further described below in conjunction wtih the drawing which is a diagrammatic flow sheet of a preferred embodiment of the process.

Bitumen derived from tar sands is fed by line 1 to distillation tower 2. Suitable bitumens have distillation characteristics such that 50% of the material is distilled at a temperature in the range of 800-1100 F. The bitumens contain 1.5-6 wt. percent sulfur, 0.1 to 1.0 wt. percent nitrogen, 100-500 p.p.m. metals, less than 5% inorganic solids andvwaterandtheymhave pour points 4in the range of 20-110 F. In tower 2 the bitumen is separated into a virgin fraction overhead fraction having an end point of 500-1000 F., preferably below 700 F. and a bottoms fraction boiling ibelow 500-1000 F., preferably above 700 F. The virgin fraction is passed by line 3 to hydroning reactor 4 without any further treatment. The bottoms is passed by line 5 to a conversion unit, preferably a fluid coker 6 or a visebrea'ker. The conversion unit can be any suitable type of thermal cracking or depolymeriza- 3,480,540 Patented Nov. 25, 1969 ICC tion reactor including a delayed coker, a fluid coker, a visbreaker, a hydrovisbreaker or the like. If desired, cracking processes involving inert solids, catalysts, hydrogen and steam can be used although conventional thermal cracking processes are deemed more suitable for cracking the heavy bitumen bottoms. In the case of fluid coking the coking zone is usually maintained at a temperature of about SOO-950 F. Typical fluid coking processes, thermal cracking processes and visbreaking processes are described in Hydrocarbon Processing, September 1966, vol. 45, No. 9, pp. 191-194. Cracking severity can be controlled in accordance with the type of products desired. Coke is removed from the coker by line 7. A gas and light ends fraction is removed from the coker by line 8. A cracked fraction boiling in the range of C5 to 1100 F. preferably 70-925 F. is passed by line 9 to line 3 where it is blended with the virgin fraction.

The blend is hydroned in reactor 4. Any suitable hydroning reactor can be used. Conventional hydroning catalysts can be used. Such catalysts include oxides and sulfides of metals of Groups VI and VIII of the Periodic Table such as cobalt, molybdenum, iron, nickel and tungsten or mixtures thereof. The metal salts are supported on a suitable porous support material such as alumina, silicaalumina, bauxite, magnesia and the like. The preferred catalyst is one containing 2 to 5 wt. percent cobalt oxide, 10-25 wt. percent molybdenum oxide and the balance silica stabilized alumina. Oxide catalysts are preferably sulided in any conventional manner prior to use or in situ.

The reaction conditions in reactor 4 depend in part on the characteristics of the components of the blended feed and on the type of products desired. In general the reaction temperature is about SOO-850 F., preferably 600-800" F.; the reaction pressure is about 40G-2000 p.s.i.g., preferably 500-1200 p.s.i.g. and the fresh feed rate is 0.2 to 3.0 v./v./hr. The hydrogen containing treat gas contains 60-100% hydrogen and it is supplied at the rate of SOO-2000 s.c.f./ bbl. Under these conditions hydrodesulfurization, hydrodenitrogenation and saturation of olens and polyaromatics are the dominant reactions.

Reaction products are removed by line 10 and passed to separator 11. A gas fraction containing hydrogen, HES and ammonia is passed overhead by line 12. All or part of the gas is recycled to the reactor by lines 13 and 14. Make up hydrogen is supplied by line 14. Part of the gas can be purged from the system or sent to purification by line 15.

Hydroned oil is passed by line 16 to distillation tower 17. In a preferred embodiment, three fractions are recovered. A C5 to 375 F. gasoline fraction is recovered by line 18. A light gas oil fraction boiling in the range of S-700 F. is recovered by line 19.. A heavy gas oil fraction boiling in the range of 700 to 1100 F. is recovered by line 20. The fractionation in zone 17 can be arranged in any suitable manner depending upon the number and type of products desired.

Example Hydrofning of blended bitumen fractions is demonstrated 'by the following data. A blend of coker distillates and virgin distillates simulating a tar sand bitumen distillate blend was prepared. The blend contained 37 vol. percent virgin gas oil from a tar sand bitumen and 63 vol. percent of petroleum-derived materials having characteristics similar to distillates derived from tar sands. The properties of the components of the blend are shown in Table I.

The simulated distillate blend and its fractions have the inspections shown in Table II.

12,000 grams of the total blend of Table II was hydrofined in a reactor in the presence of a sulfided cobalt molybdate on silica stabilized alumina catalyst. The catalyst contained 3.5 Wt. percent cobalt oxide, 12.1 Wt. percent molybdenum oxide, 2.0 Wt. percent silica and the balance was alumina. The pressure was 800 p.s.i.g.; the space velocity was 1.0 and the hydrogen rate was 2000 s.c.f./b. Table III shows the results for hydroiining terriperatures of 650 F., 700 F. and 750 F.

The data show that the bromine No. and the sulfur content of the total feed have been reduced to satisfactory values. Sulfur has been reduced from about 2% to about 0.3% or less depending on the reaction temperature. The product naphtha fraction has a bromine No. of less than 1.0 which is desirable for gasoline components. The nitrogen and sulfur content of the naphtha is low enough for subsequent reforming and/or incorporation into mogas Without sweetening. Light gas oils are often used as domestic heating oils and the light gas oil products of Table III are low enough in sulfur content for this use. The heavy gas oil product has a sulfur content of 0.5% or less making it suitable for use as industrial fuel oil in areas Where sulfur contents must be very loW.

The process of the present invention, which features the use of a single hydroner, provides considerable savings in investment and operating costs over the conventional hydroning approach to bitumens from tar sands which involves separate hydroners for naphthas, light gas oils and heavy gas oils.

We claim:

1. A process for hydrofining fractions obtained from tar sand bitumen comprising the steps of:

(a) Separating the bitumen into a virgin overhead fraction boiling below 500 to 1000 F. and a bottoms fraction boiling above about 500 to 1000 F.,

(b) Cracking the bottoms fraction to provide a cracked fraction boiling in the range of from about 50 to about 1100 F.,

(c) Blending the virgin fraction and the cracked fraction,

(d) Contactingy the blend at hydroiining conditions under a pressure of 400-2000 p.s.i.g. with a hydrogen containing gas and a hydroiining catalyst,

TABLE I.COMPONENTS IN SIMULATED ATHABASCA TAR SAND DISTILLATE BLEND l LV percent Boiling Gravity Sulphur, Nitrogen, Bromine in Blend Range, F. API Wt. percent Wt. percent N o.

Naphtha:

Coker 14 C15/350 62. 9 0. 36 0. 006 73 Virgin..T 1 (l5/380 63. 6 0.06 2 1 1 Light Gas O11:

1 The heavy virgin gas oil was produced from Athabasca Tar Sand bitumen. Other components .from topping and delayed coking unit when processing sour blend crude.

2 Parts per million.

TABLE II.-INSPECTIONS ON THE SIMULATED TAR SAND DISTILLATE BLEND AND ITS FRACTIONS Fractions Light Heavy Total Naph- Gas Gal Blend tha Oil O s LV, Percent on Blend 100 16. 8 84. 7 48. 1 ASTM Dist. Range, F C5/1.,000 126/378 420/620 692/911 Nominal (95% pt) API Gravity 28. 3 58. 5 32. 5 16. 5 Bromine Number 20. 5 65. 9 l5. 9 12. 2 Sulphur, Wt. Percent 1. 97 0. 36 1. 17 2. 82 Total Nitrogen, p.p.m l, 030 350 2, 3u0 Basic Nitrogen, p.p.m 291 25 139 533 Mercaptan N umber 28. 8 66. 4 19. 2 8. 0

(e) And recovering said blend substantially reduced in sulfur content.

2. Process according to claim 1 in which the cracking step (b) is fluid coking.

3. Process according to claim 1 in which the cracking step (b) is delayed coking.

4. Process according to claim 1 in which the cracking step (b) is visbreaking.

5. Process according to claim 1 in which the cracking step (b) is hydrovisbreaking.

6. Process according to claim 1 in which the active metals hydroning catalyst comprise a mixture of a Group VI metal and a Group VIII metal.

7. Process according to claim 1 in which the catalyst is sulded cobalt molybdate on silica alumina.

TABLE IIL-COMBO HYDROFINING SIMULATED TAR SAND DISTILLATE BLEND Treat Temperature, F.

Total Liquid Product:

Bromine Number 2. 1 2. 1 2. 5 Sulfur, Wt. Percent.. 0. 29 0. 10 0.03

Fraction l Naph Lt. G.O Hvy. G.O. Naph. Lt. G.O. Hvy. G.O. Naph. Lt. G.O. Hvy. G O

LV Percent on Total Prod 17 39 44 18 39 43 21 43 36 API Gravity 58. 9 33. 9 22. 2 59. 4 34. 1 22. 9 58. 5 33. 4 23. 8 Bromiue Number 0.3 1. 3 3. 5 0.3 1. 5 3. 3 0. 6 2. 2 4. 4 Sulfur, Weight Percent 2 16 0. 10 0. 55 2 17 0. 05 0. 19 2 16 0.01 0. 04 Total N, p.p.m 15 225 1, 350 6 134 1, 170 7 66 168 Basic N, p.p.m 15 130 288 6 90 217 6 52 60 Mercaptan Number 0. 2 0. 2 0.6 0. 1 0.1 0. 2 0. 2 0. 1 0. 2

l 15/5 distillation to nominal (J5/380, 380/650 and 650 F.l vapor temperature fractions.

2 Parts per million.

8. Process according to claim 1 in which the catalyst While the detailed description and examples of the inis nickel molybdate on alumina.

vention have shown the results and benefits obtainable with thermally cracked materials from a coker, equivalent results will be obtained with distillates from a visbreaker, a hydrovisbreaker or any similar thermal cracking unit employed for cracking bitumens or tars.

9. A process .according to claim 1 in which the separation step (a) is distillation.

10. A process for hydroiining bitumen from tar sand having a 50% boiling point in the range of 800-l100 F. comprising the steps of:

(a) Distilling the bitumen to obtain a virgin overhead fraction boiling above 700 F. and a bottoms fraction boiling below 700 F.,

(b) Coking the bottoms fraction to produce a cracked fraction boiling in the range of 70-925 F.,

(c) Blending the virgin fraction and the cracked fraction,

(d) Contacting the blend in a single stage reaction at a temperature in the range of 60G-800 F., at a feed rate of 0.2 to 3.00 v./v./hr. with 500-2000 scf/bbl. of hydrogen 'under a pressure of 500-1200 p.s.i.g. and :a hydroning catalyst comprising sulded cobalt molybdate on silica-alumina. (e) And recovering low sulfur naphtha, light gas oil and heavy gas oil fractions. 11. The process of claim 10 in which the blending, contacting and recovery steps (c) and (e) are as follows: (c) `Blending coker and virgin hydrocarbon fractions such that the blend has the following composition:

Naphtha: LV percent Coker 14 Virgin 1 Light gas oil:

Coker 12 Virgin 20 6 Heavy gas oil: LV percent Coker 16 Virgin 37 said blend having a boiling range from C5 to 1000 F. 5 (d) Contacting the blend at a temperature between 650 and 750 F. and at a pressure of 800 p.s.i.g. with hydrogen and hydroning catalyst (e) And recovering said blend substantially reduced in sulfur content.

References Cited UNITED STATES PATENTS U.S. Cl. X.R. 

